in and out是什么英语语法成分?

用作副词 (adv.)
I don't mind the children's comings and gongs.我并不介意孩子们进进出出.
We saw the comings and goings of the visitors from our window.从我们的窗户,我们可以看到进进出出的来访者.
The boss is in and out of the office all the time.
这句话的意思是：老板不停地进进出出办公室.
再问： is 后面可以直接跟副词?
再答： 可以。be属于动词，所以副词可以修饰形容词和动词。 例如He is in. He is off. He was in and out of consciousness. 他的眼睛充满了痛苦和失望。 in and out 好像不是副词~网上查不到这个词的词性~ 有进进出出, 弯弯曲曲的意思,也可以形容呼吸不匀